1. Field of the Invention
The present invention relates generally to a mobile broadcasting system. More particularly, the present invention relates to a roaming service method in a mobile broadcasting system, and a system thereof.
2. Description of the Related Art
The mobile communication market continuously requires production of new services through recombination or integration of the existing technologies. Today, with the development of communication and broadcast technologies, the conventional broadcasting system or mobile communication system has reached a phase of providing broadcast services through portable terminals (or mobile terminals), such as mobile phone and personal digital assistant (PDA). Due to the latent and actual market needs and an increasing demand for multimedia services, service providers' intended strategies for providing new services such as broadcast service in addition to the existing voice service, and identified interests of Information Technology (IT) companies which are bolstering their mobile communication businesses to meet user's demands, convergence of the mobile communication service and the Internet Protocol (IP) now becomes a mainstream of development of a next generation mobile communication technologies.
Open Mobile Alliance (OMA), a group for studying the standard for interworking between individual mobile solutions, serves to define various application standards for mobile games and Internet services. Within the OMA working groups, Open Mobile Alliance Browser and Content Mobile Broadcast Sub Working Group (OMA BAC BCAST) currently makes research on technology for providing broadcast services using mobile terminals. A brief description will now be made of the mobile broadcasting system which is under discussion in OMA.
In a mobile broadcasting system, a mobile terminal desiring to receive a broadcast service should receive so-called service guide information containing description information for the service itself, billing information for the service, and information on a receiving method for the service. The mobile terminal receives the corresponding service using the service guide information.
A description of conventional technology and novel technology will be made herein based on OMA BCAST technology, which is one of mobile broadcasting technologies, by way of example.
FIG. 1 is a diagram illustrating a logical structure of an application layer and its lower transport layer for mobile broadcast service, established by a BCAST working group of OMA.
Logical entities shown in FIG. 1 will first be described in detail. A Content Creation (CC) 101 provides contents for BCAST service, and the contents may include the common broadcast service file, for example, movie, audio and video data. In addition, the Content Creation 101 generates a service guide and provides a BCAST Service Application (BSA) 102 with an attribute for the contents, used for determining a transport bearer where the service is to be transmitted. The BCAST Service Application 102 receives BCAST service data provided from the Content Creation 101, and handles the received data in the form appropriate for providing media encoding, content protection and interaction service. Further, the BCAST Service Application 102 provides an attribute for the contents provided from the Content Creation 101 to a BCAST Service Distribution/Adaptation (BSDA) 103 and a BCAST Subscription Management (BSM) 104.
The BCAST Service Distribution/Adaptation 103 performs such operations as file/streaming transmission, service collection, service protection, service guide generation/delivery, and service notification, using BCAST service data provided from the BCAST Service Application 102. In addition, the BCAST Service Distribution/Adaptation 103 adapts the service such that it should be suitable for a Broadcast Distribution System (BDS) 112.
The BCAST Subscription Management 104 prescribes such service as a subscription and billing-related function for a BCAST service user, prescribes information used for the BCAST service, and manages a terminal receiving the BCAST service by hardware or software.
A Terminal 105 receives such program resource information as a content/service guide and content protection, and provides a broadcast service to a user. A BDS Service Distribution (BDS-SD) 111 transmits a mobile broadcast service to a plurality of terminals through mutual communication with the Broadcast Distribution System 112 and an Interaction Network (IN) 113.
The Broadcast Distribution System 112 transmits mobile broadcast service through a broadcast channel. For example, the mobile broadcast service can include Multimedia Broadcast Multicast Service (MBMS) of 3rd Generation Project Partnership (3GPP), Broadcast Multicast Service (BCMCS) of 3rd Generation Project Partnership 2 (3GPP2), and DVB-Handheld (DVB-H) or Internet Protocol (IP)-based broadcast/communication network of Digital Video Broadcasting (DVB). The Interaction Network 113 provides an interaction channel. For example, the Interaction Network 113 can be a cellular network.
A description will now be made of reference points, which are connection paths between the logical entities. The reference point can have a plurality of interfaces according to purpose, and such an interface is used for communication between more than two logical entities for a specific purpose. A message format and protocol for this is applied.
BCAST-1 121 is a transmission path of content and content attribute, and BCAST-2 122 is a transmission path of content-protected or content-unprotected BCAST service, attribute of the BCAST service, and content attribute.
BCAST-3 123 is a transmission path of attribute of BCAST service, attribute of content, user preference and subscription information, user request, and response to the request. BCAST-4 124 is a transmission path of notification message, attribute used for service guide, and key used for content protection and service protection.
BCAST-5 125 is a transmission path of protected BCAST service, unprotected BCAST service, content-protected BCAST service, content-unprotected BCAST service, BCAST service attribute, content attribute, notification, service guide, security material such as Digital Right Management (DRM) Right Object (RO) and key value used for BCAST service protection, and all data and signals transmitted through a broadcast channel.
BCAST-6 126 is a transmission path of protected BCAST service, unprotected BCAST service, content-protected BCAST service, content-unprotected BCAST service, BCAST service attribute, content attribute, notification, service guide, security material such as DRM RO and key value used for BCAST service protection, and all data and signals transmitted through an interaction channel.
BCAST-7 127 is a transmission path of service provisioning, subscription information, device management, and user preference information transmitted through an interaction channel of control information related to reception of security material such as DRM RO and key value used for BCAST service protection.
BCAST-8 128 is a transmission path through which user data for BCAST service is interacted. BDS-1 129 is a transmission path of protected BCAST service, unprotected BCAST service, BCAST service attribute, content attribute, notification, service guide, and security material such as DRM RO and key value used for BCAST service protection.
BDS-2 130 is a transmission path of service provisioning, subscription information, device management, and security material such as DRM RO and key value used for BCAST service protection. X-1 131 is a reference point between the BDS Service Distribution 111 and the Broadcast Distribution System 112. X-2 132 is a reference point between the BDS Service Distribution 111 and the Interaction Network 113. X-3 133 is a reference point between the Broadcast Distribution System 112 and the Terminal 105. X-4 134 is a reference point between the BDS Service Distribution 111 and the Terminal 105 via the broadcast channel. X-5 135 is a reference point between the BDS Service Distribution 111 and the Terminal 105 via the interaction channel. X-6 136 is a reference point between the Interaction Network 113 and the Terminal 105.
FIG. 2 is a diagram illustrating a structure of a service guide used for receiving a broadcast service in a general mobile broadcasting system. This structure is proposed in OMA BAC BCAST to provide broadcast service to a mobile terminal. One service guide is composed of a plurality of fragments each having its own purpose, and the fragments are classified into 4 groups according to use, as shown in FIG. 2.
FIG. 2 illustrates an exemplary service guide composed of an Administrative group 200, a Provisioning group 210, a Core group 220, and an Access group 230. In FIG. 2, a solid line connecting the fragments means mutual reference between the fragments.
The Administrative group 200, a group for providing basic information needed by a mobile terminal to receive a service guide, includes a Service Guide Context fragment 201 and a Service Guide Delivery Descriptor fragment 202.
The Service Guide Context fragment 201 provides a service guide identifier (ID), identification information of the service provider that generated and transmitted the service guide, and the entire information on the service guide. The Service Guide Delivery Descriptor fragment 202 provides a channel capable of receiving a plurality of service guide fragments, scheduling information, and update information to a mobile terminal so that the mobile terminal may receive only the necessary service guide at an appropriate time.
The Provisioning group 210, a group for providing charging information for service reception, includes a Purchase Item fragment 211, a Purchase Data fragment 212, and a Purchase Channel fragment 213. The Purchase Item fragment 211 provides charging information for a service or a service bundle, the Purchase Data fragment 212 indicates actual price information for a purchase item, and the Purchase Channel fragment 213 provides information on the system where the service user can actually purchase the service, and a payment method.
The Core group 220, a group for providing information on the service itself, includes a Service fragment 221, a Schedule fragment 222, and a Content fragment 223. The Service fragment 221 provides a description of the service itself that the user will receive, and also provides information indicating with which content the service can be configured. The Schedule fragment 222 provides information on the time at which the service can be provided and used. The Content fragment 223 provides information on a plurality of contents constituting the service.
The Access group 230 includes an Access fragment 231 and a Session Description fragment 232, and provides service access information indicating how to receive the services provided through the Core group 220, and detailed information on the session in which the contents constituting the corresponding service are transmitted to allow the mobile terminal to access the corresponding service.
The Access fragment 231 provides a plurality of access methods for one service to the mobile terminal, thereby providing a method capable of accessing various additional services based on one service. The Session Description fragment 232 provides session information for the service defined in one access fragment. In addition, the service guide information, as shown in FIG. 2, can further include a Preview Data fragment 224 that provides preview and icon for the service and content in addition to the foregoing four fragments.
FIG. 3 is a diagram illustrating a roaming procedure performed when a mobile broadcasting terminal desires to receive broadcast service not in a service area of its Home Network (Home N/W) 310, but in a service area of a Visited Network (Visited N/W) 320 in OMA BCAST. Before a description of each step in the roaming procedure is given, each entity of FIG. 3 will first be described.
BCAST Service Applications (BSAs) 311 and 321 in the Home N/W 310 and the Visited N/W 320 are equal in function to the BCAST Service Application 102 of FIG. 1, so they are separately shown to differentiate the BSA in the Home N/W 310 from the BSA in the Visited N/W 320 during roaming. Similarly, BCAST Subscription Managements (BSMs) 312 and 322 have the same function as that of the BCAST Subscription Management 104 of FIG. 1. BCAST Service Distribution Adaptations (BSDAs) 313 and 323 have the same function as that of the BCAST Service Distribution/Adaptation 103 of FIG. 1, and group entities 314 and 324, each composed of BDS Service Distribution (BDS-SD), BCAST Distribution System (BDS) and/or Interaction Network (IN), have the same function as the group entity of the BDS-SD 111, the BDS 112 and/or the IN 113 of FIG. 1. A Terminal 330 has the same function as that of the Terminal 105 of FIG. 1. Each step in the roaming procedure will now be described.
In step 301, a user requests a BCAST roaming service in its Home N/W 310, and then moves to the Visited N/W 320. A procedure for roaming from the Home N/W 310 to the Visited N/W 320 should be performed outside the BCAST area in the lower layers 313 and 323. In step 302, the Terminal 330 automatically receives a service guide from the Visited N/W 320 to which it is roaming, without connection to the Home N/W 310. In step 303, upon receiving the service guide, the Terminal 330 sends a request for Rights Object for a particular BCAST service desired by the user to the BSM 322 of the Visited N/W 320. In step 304, the BSM 322 of the Visited N/W 320 acquires authorization for user roaming to the BSM 312 of the Home N/W 310. In step 305, the BSM 322 delivers the Right Object requested by the Terminal 330 in step 303 to the Terminal 330 via the BSM 321 of the Visited N/W 320. After receiving the Right Object in step 305, the Terminal 330 receives the BCAST service via the BSDA 323 of the Visited N/W 320 in step 306. Finally, in step 307, the Visited N/W 320 generates charging information and delivers the charging information to the Home N/W 310, which is outside the BCAST standard, so a description thereof will not be given.
As described in FIG. 3, BCAST currently presents the roaming procedure. Although there is a need for a message for communication between the entities and its message format in order to actually make the roaming possible, a message for communication between the entities and its message format, they are not presented. In the mobile broadcast service where several service providers may exist, in order for user terminals to freely roam and receive the service, the message flow between BCAST service entities should be specifically presented. In the current roaming procedure, when a user has performed roaming, the procedure is achieved without notification for charging information. However, when roaming occurs actually, the charging system is different from that of the Home N/W 310, which has been used by the user, and the user is not also charged according to the charge in the service guide of the Visited N/W 320, which was received while in roaming. Because of this, there is a need for a step capable of providing information on a change in the charge to the user and allowing the user to determine whether he/she will use the roaming service. In addition, in order to make the roaming procedure possible, a request for the roaming service should be previously sent to the Home N/W 310. However, because such a situation is not always possible, the roaming should be possible even after the terminal moves the area. It is assumed in the roaming procedure of FIG. 3 that the scheme used for deciphering the enciphered content or service received in step 305 is OMA DRM 2.0. Actually, the roaming procedure should be updated such that the content or service can be enciphered/deciphered even by the schemes other than the OMA DRM 2.0. Accordingly, there is a need for an improved method for supporting a roaming service in the mobile broadcasting system.